Thermochromic multi-band compatible infrared stealth film and preparation method and application thereof

Abstract

The present application relates to a kind of thermochromic multiband compatible infrared stealth film and its preparation method and application, belong to infrared stealth film technical field.To solve the problems of existing infrared stealth material preparation process complex, high cost, narrow application, the present application provides a kind of thermochromic multiband compatible infrared stealth film, from top to bottom in turn for ZnS material layer, VO2 Material layer, Si material layer and Ag substrate layer.The infrared stealth film of the present application has the characteristics that infrared emissivity decreases with temperature rise, can be reversibly adjusted according to the change of ambient temperature Film emissivity, with 3~5 μm and 8~14 μm dual infrared band stealth function, in non-infrared detection band 5~8 μm band has higher emissivity, can realize the heat dissipation function of stealth target in this band.The infrared stealth film of the present application has the characteristics of simple structure and convenient preparation method, and the film can be large-area covered on target surface, which is conducive to large-scale promotion.

Description

Technical Field

[0001] This invention belongs to the field of infrared stealth film technology, and particularly relates to a thermochromic multi-band compatible infrared stealth film, its preparation method and application. Background Technology

[0002] With the rapid development of infrared detector technology, infrared detection methods are becoming increasingly precise and diversified, which places new and higher demands on infrared stealth technology. Based on the current state of development of infrared stealth technology, its development trend can be summarized in two aspects: one is to seek compatibility between stealth technologies across various wavelengths, and the other is to improve existing stealth methods.

[0003] The invention patent with publication number CN113534315A, entitled "An Infrared Stealth Superstructure Compatible with Thermochromatographic Emissivity and Frequency Selective Heat Dissipation", mainly includes a number of electromagnetic resonant units arranged periodically on a substrate. Each electromagnetic resonant unit includes an emissivity modulation layer and a dielectric layer stacked from bottom to top, and a number of metal pillars periodically arranged on the dielectric layer. The emissivity modulation layer is made by embedding a phase change material in the metal layer stacked on the substrate. Based on the characteristics of this infrared stealth metastructure material, although it can achieve active heat dissipation by modulating the emissivity in the atmospheric transmission window: 3-5μm and 8-14μm, and enhancing the thermal radiation in the atmospheric absorption band 5-8μm, it also has certain drawbacks: (1) The material structure is relatively complex. In the process of controlling the emissivity and selecting the frequency for thermal emission, it is necessary to strictly control parameters such as the diameter or side length, height and spacing of the metal pillars. The control process is relatively complex, the modulation requirements are high, and there are drawbacks of inconvenient control; (2) The metal pillars in the structure are made of precious metals, which increases the manufacturing cost in the actual production and use process, which is not conducive to large-scale promotion and use; (3) In the manufacturing process of 3D metamaterial structures, there are generally problems such as complicated steps, high cost and long time consumption. It is not easy to conform to the curved surface and it is difficult to meet the application conditions in actual complex situations.

[0004] Therefore, there is an urgent need in this field for infrared stealth materials that are simple to prepare, low in cost, applicable to more application scenarios, and capable of achieving multi-band compatibility and good heat dissipation performance. Summary of the Invention

[0005] To address the problems of complex manufacturing processes, high costs, and limited applications of existing infrared stealth materials, this invention provides a thermochromic multi-band compatible infrared stealth film, its preparation method, and its applications.

[0006] The technical solution of this invention:

[0007] A thermochromic multi-band compatible infrared stealth film comprises, from top to bottom, a ZnS material layer, a VO2 material layer, a Si material layer, and an Ag substrate layer. The thickness of the ZnS material layer is 300–600 nm, the thickness of the VO2 material layer is 100–250 nm, the thickness of the Si material layer is not less than 1000 nm, and the thickness of the Ag substrate layer is not less than 200 nm.

[0008] Furthermore, the thickness of the ZnS material layer is 300 nm.

[0009] Furthermore, the thickness of the ZnS material layer is 600 nm.

[0010] A method for preparing a thermochromic multi-band compatible infrared stealth film is disclosed. The method involves sequentially depositing the film on a stainless steel substrate using magnetron sputtering technology, with high-purity argon as the sputtering gas. The sputtering process is carried out in a rotating sample stage. An Ag substrate layer is prepared by sputtering with an Ag metal target under an argon atmosphere using a DC power supply. Si, VO2, and ZnS material layers are then prepared sequentially by sputtering with Si, VO2, and ZnS targets under an argon atmosphere using an RF power supply.

[0011] Furthermore, a 3-minute pre-sputtering process is performed before the formal sputtering deposition begins.

[0012] Furthermore, the rotational speed of the rotating sample stage is 5 revolutions per minute.

[0013] Furthermore, during the sputtering preparation of the Ag substrate layer, the sample is placed in the cavity and a vacuum is drawn to achieve an initial cavity pressure of 8 × 10⁻⁶. -4 After Pa, argon gas is introduced at a flow rate of 50 sccm and the pressure is controlled at 0.5 Pa. Sputtering begins after the pressure stabilizes. The DC power supply sputtering power is 20-100 W and the sputtering time is 10-60 minutes.

[0014] Furthermore, during the sputtering preparation of Si, VO2, and ZnS material layers, the sample with the completed Ag substrate layer is placed in the cavity and a vacuum is drawn until the initial cavity pressure reaches 8 × 10⁻⁶. -4 After Pa, argon gas with a flow rate of 50 sccm is introduced and the pressure is controlled at 0.5 Pa. After the pressure stabilizes, sputtering begins. The sputtering deposition of Si material layer, VO2 material layer and ZnS material layer is completed in sequence. The sputtering power of the RF power supply is 100-300W and the sputtering time is 20-60 minutes.

[0015] The application of a thermochromic multi-band compatible infrared stealth film in the field of defense and military equipment, including tanks, missiles and aircraft.

[0016] The beneficial effects of this invention are:

[0017] The thermochromic multi-band compatible infrared stealth film provided by this invention is based on the metal-semiconductor phase transition that occurs in the VO2 material layer at a critical temperature of 341K. The optical properties of the film itself change, and it has the characteristic that the infrared emissivity decreases with increasing temperature. Thus, the emissivity of the film can be adaptively and reversibly adjusted according to changes in ambient temperature. It has dual infrared band stealth functions in 3-5μm and 8-14μm, and at the same time, it has a high emissivity in the non-infrared detection band of 5-8μm, which can realize the heat dissipation function of stealth targets in this band.

[0018] This invention presents a thermochromic multi-band compatible infrared stealth film with a simple structure. The emissivity of the film in the 3–5 μm and 8–14 μm wavelength bands can be adjusted by changing the thickness of the ZnS material layer to meet the needs of different infrared stealth applications. This invention uses silver instead of precious gold, significantly reducing manufacturing costs and making it more practically applicable. The thermochromic multi-band compatible infrared stealth film is prepared using magnetron sputtering, a mature process that facilitates large-scale production. The film can cover a large area of ​​the target surface, exhibiting broader application prospects compared to traditional infrared stealth films. It is suitable for various application scenarios, including national defense and military equipment, and is conducive to large-scale promotion. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the thermochromic multi-band compatible infrared stealth film of the present invention;

[0020] Figure 2 This is a comparison of the reflectance of the thermochromic multi-band compatible infrared stealth film of Example 1 at 300K and 373K.

[0021] Figure 3 This is a comparison of the emissivity of the thermochromic multi-band compatible infrared stealth film of Example 1 at 300K and 373K.

[0022] Figure 4 This is a comparison chart of the changes in reflectance, emissivity, and transmittance of the thermochromic multi-band compatible infrared stealth film of Example 1 at 300K.

[0023] Figure 5 This is a comparison chart of the changes in reflectance, emissivity, and transmittance of the thermochromic multi-band compatible infrared stealth film of Example 1 at 373K.

[0024] Figure 6 The image shows a comparison of the reflectance of infrared stealth films with different thicknesses of ZnS material layers prepared in Examples 1-4 at 300K.

[0025] Figure 7The emissivity comparison graphs of infrared stealth films with different thicknesses of ZnS material layers prepared in Examples 1-4 at 300K are shown.

[0026] Figure 8 The image shows a comparison of the reflectance of infrared stealth films with different thicknesses of ZnS material layers prepared in Examples 1-4 at 373K.

[0027] Figure 9 The image shows a comparison of the emissivity of infrared stealth films with different thicknesses of ZnS material layers prepared in Examples 1-4 at 373K. Detailed Implementation

[0028] The technical solution of the present invention will be further described below with reference to embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention. In the following embodiments, the process equipment or apparatus not specifically specified are all conventional equipment or apparatus in the art. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commercially available; unless otherwise specified, the technical means used in the embodiments of the present invention are all conventional means well known to those skilled in the art.

[0029] Example 1

[0030] This embodiment provides a thermochromic multi-band compatible infrared stealth film, referencing... Figure 1 As shown, from top to bottom, there are ZnS material layer, VO2 material layer, Si material layer and Ag substrate layer. The thickness of ZnS material layer is 300nm, the thickness of VO2 material layer is 200nm, the thickness of Si material layer is 1000nm, and the thickness of Ag substrate layer is 200nm.

[0031] The multilayer infrared stealth film provided in this embodiment is designed based on the impedance matching principle. Ag has a higher conductivity than other metals, so at the same thickness, the Ag substrate layer exhibits low thin-film resistivity. At the same time, the Ag substrate layer has a low emissivity, which allows it to come into thermal contact with high-temperature targets during practical applications, while also serving as an infrared reflective functional layer.

[0032] The Si material layer has a high refractive index and a low absorption coefficient. As a dielectric layer, it can effectively match the impedance of the Ag substrate layer, thereby improving the performance of multilayer infrared stealth films.

[0033] In this embodiment, the top layer of the multilayer infrared stealth film is a ZnS material layer. ZnS material has good transmission performance in the infrared spectrum range, which can effectively transmit infrared light, and it also has good corrosion resistance under certain conditions, maintaining good stability in some harsh environments.

[0034] The VO2 material layer is the intelligent core layer for thin-film spectral radiation modulation. VO2 material undergoes a metal-semiconductor phase transition at its critical temperature of 341K, exhibiting a characteristic where infrared emissivity decreases with increasing temperature. This causes changes in the optical properties of the thin film itself, resulting in a reversible transition from transmission to reflection of infrared light. Therefore, the multilayer infrared stealth film in this embodiment can dynamically change its emissivity according to changes in the surface temperature of an object.

[0035] At the critical temperature of 341 K, VO2 transitions from a semiconductor state to a metallic state, resulting in increased reflectivity and decreased emissivity in the near-infrared band, enabling stealth capabilities in the infrared band. From a microscopic perspective, the changes in the VO2 crystal and band structure lead to alterations in the material's inherent properties: below the phase transition temperature, VO2 exhibits a monoclinic tetragonal crystal structure, making it transparent to infrared radiation; above the phase transition temperature, VO2 transforms into a metallic tetragonal phase, exhibiting strong reflectivity in the infrared band.

[0036] When the temperature is below 341K, the ZnS, VO2, and Si material layers are all transparent in the mid-infrared region, and the bottom layer of the film is an Ag substrate. Therefore, the multilayer film exhibits a high reflectivity in the mid-infrared region.

[0037] When the temperature exceeds 341 K, VO2 transforms from a semiconductor to a metal. The Fabry-Perot cavity effect between the ZnS material layer and the metal enhances the absorption of the film in the mid-infrared region. However, based on the stealth requirements of the target infrared band, an anti-reflection and anti-reflection layer needs to be placed on top of the film to reduce or mitigate the Fabry-Perot resonance effect. Therefore, the ZnS material layer is selected as the anti-reflection layer and placed on top of the film, which also protects the inner layer material and effectively extends the overall lifespan of the film.

[0038] In this embodiment, the thermochromic smart dual-band infrared stealth film is prepared by magnetron sputtering, and the specific steps are as follows:

[0039] Step 1: Magnetron sputtering is used to deposit gas sequentially onto a clean stainless steel substrate. High-purity argon gas (99.99% purity) is used as the sputtering gas, and the process is maintained at room temperature. To ensure sputtering uniformity, the entire sputtering process is performed on a rotating sample stage at a speed of 5 rpm. Before the actual sputtering begins, a 3-minute pre-sputtering is performed to effectively remove impurities from the target surface.

[0040] Step 2: For the Ag substrate layer, a 99.9% pure Ag metal target was used for sputtering under an argon atmosphere using a DC power supply. The sample was placed in the chamber and a vacuum was drawn until the initial chamber pressure reached 8 × 10⁻⁶. -4After Pa, argon gas was introduced at a flow rate of 50 sccm, and the pressure was controlled at 0.5 Pa. Sputtering was started after the pressure stabilized, with a DC power supply of 100 W and a sputtering time of 20 minutes.

[0041] Step 3: For the Si, VO2, and ZnS material layers, sputtering was performed using RF power supply with 99.9% pure Si, 99.9% pure VO2, and 99.9% pure ZnS targets respectively under an argon atmosphere. The sample with the completed Ag substrate layer was placed in the cavity and a vacuum was drawn until the initial cavity pressure reached 8 × 10⁻⁶. -4 After Pa, argon gas was introduced at a flow rate of 50 sccm, and the pressure was controlled at 0.5 Pa. Sputtering was started after the pressure stabilized. The sputtering power of the RF power supply was 200W. The sputtering time for the Si material layer was 50 min, the sputtering time for the VO2 material layer was 20 min, and the sputtering time for the ZnS material layer was 30 min.

[0042] The selection of specific sputtering power and time parameters fully considers the performance requirements of the thin film and the optimization of the preparation process to ensure the quality and uniformity of the obtained film.

[0043] Example 2

[0044] This embodiment provides a thermochromic multi-band compatible infrared stealth film, which consists of a ZnS material layer, a VO2 material layer, a Si material layer and an Ag substrate layer from top to bottom. The thickness of the ZnS material layer is 400 nm, the thickness of the VO2 material layer is 200 nm, the thickness of the Si material layer is 1000 nm, and the thickness of the Ag substrate layer is 200 nm.

[0045] The preparation method of the thermochromic multi-band compatible infrared stealth film in this embodiment is the same as that in Example 1, except that the sputtering time varies depending on the film thickness.

[0046] Example 3

[0047] This embodiment provides a thermochromic multi-band compatible infrared stealth film, which consists of a ZnS material layer, a VO2 material layer, a Si material layer and an Ag substrate layer from top to bottom. The thickness of the ZnS material layer is 500 nm, the thickness of the VO2 material layer is 200 nm, the thickness of the Si material layer is 1000 nm, and the thickness of the Ag substrate layer is 200 nm.

[0048] The preparation method of the thermochromic multi-band compatible infrared stealth film in this embodiment is the same as that in Example 1, except that the sputtering time varies depending on the film thickness.

[0049] Example 4

[0050] This embodiment provides a thermochromic multi-band compatible infrared stealth film, which consists of a ZnS material layer, a VO2 material layer, a Si material layer and an Ag substrate layer from top to bottom. The thickness of the ZnS material layer is 600 nm, the thickness of the VO2 material layer is 200 nm, the thickness of the Si material layer is 1000 nm, and the thickness of the Ag substrate layer is 200 nm.

[0051] The preparation method of the thermochromic multi-band compatible infrared stealth film in this embodiment is the same as that in Example 1, except that the sputtering time varies depending on the film thickness.

[0052] Example 5

[0053] This embodiment provides a thermochromic multi-band compatible infrared stealth film, which consists of a ZnS material layer, a VO2 material layer, a Si material layer and an Ag substrate layer from top to bottom. The thickness of the ZnS material layer is 300 nm, the thickness of the VO2 material layer is 100 nm, the thickness of the Si material layer is 1000 nm, and the thickness of the Ag substrate layer is 200 nm.

[0054] The preparation method of the thermochromic multi-band compatible infrared stealth film in this embodiment is the same as that in Example 1, except that the sputtering time varies depending on the film thickness.

[0055] Example 6

[0056] This embodiment provides a thermochromic multi-band compatible infrared stealth film, which consists of a ZnS material layer, a VO2 material layer, a Si material layer and an Ag substrate layer from top to bottom. The thickness of the ZnS material layer is 300 nm, the thickness of the VO2 material layer is 150 nm, the thickness of the Si material layer is 1000 nm, and the thickness of the Ag substrate layer is 200 nm.

[0057] The preparation method of the thermochromic multi-band compatible infrared stealth film in this embodiment is the same as that in Example 1, except that the sputtering time varies depending on the film thickness.

[0058] Example 7

[0059] This embodiment provides a thermochromic multi-band compatible infrared stealth film, which consists of a ZnS material layer, a VO2 material layer, a Si material layer and an Ag substrate layer from top to bottom. The thickness of the ZnS material layer is 300 nm, the thickness of the VO2 material layer is 200 nm, the thickness of the Si material layer is 1000 nm, and the thickness of the Ag substrate layer is 200 nm.

[0060] The preparation method of the thermochromic multi-band compatible infrared stealth film in this embodiment is the same as that in Example 1, except that the sputtering time varies depending on the film thickness.

[0061] Example 8

[0062] This embodiment provides a thermochromic multi-band compatible infrared stealth film, which consists of a ZnS material layer, a VO2 material layer, a Si material layer and an Ag substrate layer from top to bottom. The thickness of the ZnS material layer is 300 nm, the thickness of the VO2 material layer is 250 nm, the thickness of the Si material layer is 1000 nm, and the thickness of the Ag substrate layer is 200 nm.

[0063] The preparation method of the thermochromic multi-band compatible infrared stealth film in this embodiment is the same as that in Example 1, except that the sputtering time varies depending on the film thickness.

[0064] Comparative experiments and results on the reflectivity and emissivity of infrared stealth films at different temperatures, and comparative experiments and results on their heat dissipation effects.

[0065] 1. Comparative experiment and results of reflectivity and emissivity of infrared stealth films at different temperatures.

[0066] 300K and 373K are defined as the cold and hot states of the thermal environment in which the infrared stealth film exists, respectively. Figure 2 This is a comparison of the reflectance of the thermochromic multi-band compatible infrared stealth film of Example 1 at 300K and 373K. Figure 3 This is a comparison of the emissivity of the thermochromic multi-band compatible infrared stealth film of Example 1 at 300K and 373K.

[0067] Figure 2 and Figure 3 The results show that, under cold conditions, the thin film exhibits high reflectivity and low emissivity in the 3–12 μm band; in the 12–14 μm band, the reflectivity and emissivity of the thin film change in opposite directions.

[0068] Under hot conditions, the overall reflectivity of the thin film remains above 0.2 in the 3–14 μm band, and decreases slightly in the 3–12 μm band compared to the cold condition; within the 12–14 μm range, the reflectivity remains around 0.8. The overall emissivity of the thin film remains below 0.2 in the infrared detection band of 8–14 μm, exhibiting good infrared stealth performance.

[0069] A comprehensive analysis was conducted on the changes in reflectivity, emissivity, and transmittance of the infrared stealth film under thermal conditions of 300K and 373K. Figure 4 This is a comparison chart of the changes in reflectance, emissivity, and transmittance of the thermochromic multi-band compatible infrared stealth film of Example 1 at 300K. Figure 5 This is a comparison chart showing the changes in reflectivity, emissivity, and transmittance of the thermochromic multi-band compatible infrared stealth film of Example 1 at 373K.

[0070] The results show that the 200nm thick Ag substrate is the infrared reflection functional layer of the infrared stealth film as a whole, the VO2 material layer in the middle is the infrared radiation modulation functional layer in the multilayer film structure of the infrared stealth film, and the dielectric ZnS material layer modulates the spectral selectivity of the multilayer film by changing the transmission path of electromagnetic waves in the multilayer film.

[0071] according to Figure 4 , Figure 5 The infrared spectrum curves of the infrared stealth film show that its transmittance in the infrared band is 0. Comparing the changes in the overall optical properties of the infrared stealth film under 300K and 373K conditions reveals that as the ambient temperature increases from 300K to 373K, the reflectance of the film decreases in the 3–12μm band, while the reflectance increases in the 12–-14μm band, with the overall transmittance remaining at 0. Therefore, the emissivity of the film in this band changes inversely to its reflectance, and the emissivity in the 8–14μm band remains consistently below 0.2.

[0072] The aforementioned changes are advantageous for the stealth of targets in the 8–14 μm band. However, for another infrared detection band of 3–5 μm, the temperature rise from 300 K to 373 K will increase the overall emissivity of the thin film in this band, which is detrimental to the stealth of high-temperature targets.

[0073] Simulation results demonstrate that the designed infrared stealth film can dynamically adjust its emissivity under the influence of thermal environment changes, thereby achieving target stealth; in another infrared detection band of 3-5 μm, the temperature rise of the thermal environment will correspondingly increase the overall emissivity of the film.

[0074] In summary, the above-mentioned thin film can be used for infrared stealth of high-temperature targets in the 8-14 μm band.

[0075] 2. The effect of ZnS material layer thickness variation on the performance of infrared stealth films.

[0076] Based on the thin film with a ZnS material layer thickness of 300 nm in Example 1, the emissivity and reflectivity of the thin films with ZnS material layer thicknesses of 400 nm, 500 nm and 600 nm in Examples 2-4 were calculated and analyzed respectively. Figure 6 The image shows a comparison of the reflectance of infrared stealth films with different thicknesses of ZnS material layers prepared in Examples 1-4 at 300K. Figure 7 The image shows a comparison of the emissivity of infrared stealth films with different thicknesses of ZnS material layers prepared in Examples 1-4 at 300K.

[0077] The results show that the film maintains high reflectivity throughout the 3–11 μm wavelength range, with a reflectivity above 0.9. Within the 11–14 μm wavelength range, the reflectivity gradually decreases, dropping to less than 0.1 at 14 μm. Considering the variation in ZnS material thickness, the overall reflectivity of the film does not change significantly; variations in the 300 nm ZnS material layer thickness have less than a 0.1 effect on the overall reflectivity. These findings indicate that variations in the ZnS material layer thickness within the 300 nm range do not significantly affect the cold-state reflectivity of the film.

[0078] Existing calculations show that a 300nm thick ZnS layer, compared to 600nm, results in higher reflectivity in the 8–14μm wavelength range. However, in the 3–5μm wavelength range, ZnS thicknesses of 300nm, 400nm, 500nm, and 600nm have irregular effects on the overall reflectivity of the film, with variations less than 0.1%. The overall emissivity of the cold-state film exhibits the opposite trend to that of the reflectivity. In conclusion, the calculated variations in ZnS layer thickness (300nm, 400nm, 500nm, and 600nm) do not significantly affect the reflectivity or emissivity of the cold-state film.

[0079] Figure 8 The image shows a comparison of the reflectance of infrared stealth films with different thicknesses of ZnS material layers prepared in Examples 1-4 at 373K. Figure 9 The image shows a comparison of the emissivity of infrared stealth films with different thicknesses of ZnS material layers prepared in Examples 1-4 at 373K.

[0080] Table 1 shows the effect of ZnS thickness variation on the emissivity of the film at 300K and 373K.

[0081] Table 1

[0082]

[0083] Figure 8 , Figure 9 The results in Table 1 show that after the metal-semiconductor phase transition of VO2 in the thin film, the overall optical properties of the film change drastically. The reflectivity in the 3–14 μm wavelength range decreases compared to the cold state. A 300 nm thick ZnS layer results in a peak reflectivity of 0.8 and a minimum reflectivity of 0.25. With increasing ZnS layer thickness, the minimum reflectivity of the hot-state film shifts towards increasing wavelength, and the peak reflectivity gradually increases at each thickness. Therefore, it can be determined that the location of the peak reflectivity can be controlled by appropriately selecting the ZnS layer thickness.

[0084] The overall emissivity results of the thin film show that ZnS material layers with a thickness of 300 nm to 600 nm all result in an emissivity of less than 0.4 in the 8 to 14 μm band; for another infrared detection band of 3 to 5 μm, the thin film with a ZnS material layer with a thickness of 600 nm has an even lower overall emissivity.

[0085] Infrared stealth films not only need to have low emissivity in the detection band, but also ideally possess high emissivity in the non-detection band to achieve good heat dissipation. A 600nm thick ZnS film can fully meet these requirements. When meeting the infrared stealth requirements for a single-band target: in the 8–14μm band, a 300nm thick ZnS film provides superior overall performance; while in the 3–5μm band, a 600nm thick ZnS film exhibits better stealth performance. Considering all bands, a 600nm thick ZnS film is the preferred choice for achieving dual-band stealth requirements.

Claims

1. A thermochromic multi-band compatible infrared stealth film, characterized in that, From top to bottom, the layers are a ZnS material layer, a VO2 material layer, a Si material layer, and an Ag substrate layer. The thickness of the ZnS material layer is 300, 400, 500, or 600 nm, the thickness of the VO2 material layer is 100-250 nm, the thickness of the Si material layer is not less than 1000 nm, and the thickness of the Ag substrate layer is not less than 200 nm.

2. A method for preparing a thermochromic multi-band compatible infrared stealth film as described in claim 1, characterized in that, Magnetron sputtering was used to deposit materials sequentially on a stainless steel substrate, with high-purity argon as the sputtering gas. The sputtering process was carried out in a rotating sample stage. Ag substrate layers were prepared by sputtering with an Ag metal target under an argon atmosphere using a DC power supply. Si material layers, VO2 material layers, and ZnS material layers were prepared sequentially by sputtering with an argon atmosphere using an RF power supply, respectively.

3. The method for preparing a thermochromic multi-band compatible infrared stealth film according to claim 2, characterized in that, A 3-minute pre-sputtering process is performed before the actual sputtering deposition begins.

4. The method for preparing a thermochromic multi-band compatible infrared stealth film according to claim 2 or 3, characterized in that, The rotating sample stage rotates at a speed of 5 revolutions per minute.

5. The method for preparing a thermochromic multi-band compatible infrared stealth film according to claim 4, characterized in that, During sputtering preparation of Ag substrates, the sample is placed in a cavity and a vacuum is drawn to achieve an initial cavity pressure of 8 × 10⁻⁶. -4 After Pa, argon gas is introduced at a flow rate of 50 sccm and the pressure is controlled at 0.5 Pa. Sputtering begins after the pressure stabilizes. The DC power supply sputtering power is 20~100W and the sputtering time is 10~60 minutes.

6. The method for preparing a thermochromic multi-band compatible infrared stealth film according to claim 5, characterized in that, When sputtering Si, VO2, and ZnS material layers, the sample with the completed Ag substrate layer is placed in the cavity and a vacuum is drawn until the initial cavity pressure reaches 8 × 10⁻⁶. -4 After Pa, argon gas with a flow rate of 50 sccm is introduced and the pressure is controlled at 0.5 Pa. After the pressure stabilizes, sputtering begins. The sputtering power of the RF power supply is 100~300W and the sputtering time is 20~60 minutes. The sputtering deposition of Si material layer, VO2 material layer and ZnS material layer is completed in sequence.

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